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drm/amdgpu: Fix AMDGPU_GTT_MAX_TRANSFER_SIZE for non-4K systems

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Running RCCL unit tests on a system with a 64K PAGE_SIZE triggers
the following warning and causes the test to terminate on latest
upstream kernel:

WARNING: drivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1335 at
amdgpu_bo_release_notify+0x1bc/0x280 [amdgpu],
CPU#18: rccl-UnitTests/33151

Call trace:
amdgpu_bo_release_notify
ttm_bo_release
amdgpu_gem_object_free
drm_gem_object_free
amdgpu_bo_unref
amdgpu_bo_create
amdgpu_bo_create_user
amdgpu_gem_object_create
amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu
kfd_ioctl_alloc_memory_of_gpu
kfd_ioctl
sys_ioctl

The warning is triggered because
amdgpu_ttm_next_clear_entity() returns NULL when a clear buffer
operation is requested. This happens because the GART window
allocation for the default_entity, clear_entity and move_entity
fails during initialization.

Commit [1] introduced separate GART windows for the
default_entity, clear_entity and move_entity of each SDMA
instance. Their sizes are derived from
AMDGPU_GTT_MAX_TRANSFER_SIZE, which is currently defined as 1024
pages. This implicitly assumes a 4K PAGE_SIZE, where 1024 pages
correspond to a 4MB transfer. On a 64K PAGE_SIZE system, however,
the same value expands to 64MB.

The default_entity and clear_entity each allocate one
AMDGPU_GTT_MAX_TRANSFER_SIZE GART window, while the move_entity
allocates two such windows. This results in 16MB of GART space
per SDMA instance on a 4K PAGE_SIZE system, but 256MB per SDMA
instance on a 64K PAGE_SIZE system.

On an MI210 system with five SDMA instances and a 512MB GART
aperture, the total GART space required becomes 1.25GB,
exceeding the available GART aperture. Consequently, GART window
allocation fails, amdgpu_ttm_next_clear_entity() returns NULL,
and the above warning is triggered.

Redefine AMDGPU_GTT_MAX_TRANSFER_SIZE in bytes instead of page
units. Where a page count is required, convert it using
PAGE_SHIFT. This preserves the existing 4MB transfer size across
all PAGE_SIZE configurations while keeping GART window
allocations within the available GART aperture.

[1] https://lore.kernel.org/all/20260408100327.1372-3-pierre-eric.pelloux-prayer@amd.com/#t

Closes: https://gitlab.freedesktop.org/drm/amd/-/work_items/5435
Fixes: 897ee11ec0 ("drm/amdgpu: create multiple clear/move ttm entities")
Signed-off-by: Donet Tom <donettom@linux.ibm.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 27213b776a)
Cc: stable@vger.kernel.org
This commit is contained in:
Donet Tom 2026-06-25 13:22:06 +05:30 committed by Alex Deucher
parent 9c8b85f95c
commit 8b7033c0c5
3 changed files with 8 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
View File

@ -208,9 +208,10 @@ static int amdgpu_ttm_map_buffer(struct amdgpu_ttm_buffer_entity *entity,
void *cpu_addr;
uint64_t flags;
int r;
const u64 GTT_MAX_PAGES = (AMDGPU_GTT_MAX_TRANSFER_SIZE >> PAGE_SHIFT);
BUG_ON(adev->mman.buffer_funcs->copy_max_bytes <
AMDGPU_GTT_MAX_TRANSFER_SIZE * 8);
GTT_MAX_PAGES * AMDGPU_GPU_PAGES_IN_CPU_PAGE * 8);
if (WARN_ON(mem->mem_type == AMDGPU_PL_PREEMPT))
return -EINVAL;
@ -230,7 +231,7 @@ static int amdgpu_ttm_map_buffer(struct amdgpu_ttm_buffer_entity *entity,
offset = mm_cur->start & ~PAGE_MASK;
num_pages = PFN_UP(*size + offset);
num_pages = min_t(uint32_t, num_pages, AMDGPU_GTT_MAX_TRANSFER_SIZE);
num_pages = min_t(uint32_t, num_pages, GTT_MAX_PAGES);
*size = min(*size, (uint64_t)num_pages * PAGE_SIZE - offset);
@ -2033,6 +2034,7 @@ static int amdgpu_ttm_buffer_entity_init(struct amdgpu_gtt_mgr *mgr,
u32 num_gart_windows)
{
int i, r, num_pages;
const u64 GTT_MAX_PAGES = (AMDGPU_GTT_MAX_TRANSFER_SIZE >> PAGE_SHIFT);
r = drm_sched_entity_init(&entity->base, prio, scheds, num_schedulers, NULL);
if (r)
@ -2045,7 +2047,7 @@ static int amdgpu_ttm_buffer_entity_init(struct amdgpu_gtt_mgr *mgr,
if (num_gart_windows == 0)
return 0;
num_pages = num_gart_windows * AMDGPU_GTT_MAX_TRANSFER_SIZE;
num_pages = num_gart_windows * GTT_MAX_PAGES;
r = amdgpu_gtt_mgr_alloc_entries(mgr, &entity->gart_node, num_pages,
DRM_MM_INSERT_BEST);
if (r) {
@ -2056,7 +2058,7 @@ static int amdgpu_ttm_buffer_entity_init(struct amdgpu_gtt_mgr *mgr,
for (i = 0; i < num_gart_windows; i++) {
entity->gart_window_offs[i] =
amdgpu_gtt_node_to_byte_offset(&entity->gart_node) +
i * AMDGPU_GTT_MAX_TRANSFER_SIZE * PAGE_SIZE;
i * GTT_MAX_PAGES * PAGE_SIZE;
}
return 0;

2
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
View File

@ -39,7 +39,7 @@
#define AMDGPU_PL_MMIO_REMAP (TTM_PL_PRIV + 5)
#define __AMDGPU_PL_NUM (TTM_PL_PRIV + 6)
#define AMDGPU_GTT_MAX_TRANSFER_SIZE 1024
#define AMDGPU_GTT_MAX_TRANSFER_SIZE (1ULL << 22)
extern const struct attribute_group amdgpu_vram_mgr_attr_group;
extern const struct attribute_group amdgpu_gtt_mgr_attr_group;

2
drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
View File

@ -128,7 +128,7 @@ svm_migrate_copy_memory_gart(struct amdgpu_device *adev, dma_addr_t *sys,
enum MIGRATION_COPY_DIR direction,
struct dma_fence **mfence)
{
const u64 GTT_MAX_PAGES = AMDGPU_GTT_MAX_TRANSFER_SIZE;
const u64 GTT_MAX_PAGES = (AMDGPU_GTT_MAX_TRANSFER_SIZE >> PAGE_SHIFT);
struct amdgpu_ring *ring;
struct amdgpu_ttm_buffer_entity *entity;
u64 gart_s, gart_d;